What to Plant in September in Zone 4: Last Cool Sowings

In USDA zone 4, September is for last cool sowings early in the month, then cover crops. Fast greens and radishes may still fit. Skip garlic and warm crop...

Published 2026-08-31 · Reviewed 2026-10-05 by ThriveThyme

September Zone 4 September zone 4 fall planting

What to Plant in September in Zone 4

In USDA zone 4, September is for last cool sowings in the first part of the month, then cover. Most long-season fall crops are too late from seed. Fast radishes, arugula, spinach, or lettuce may still fit if the catalog window is open and frost settings allow. Skip new tomatoes, peppers, and melons. Do not plant garlic in September.

First frost often arrives in late September in many zone 4 gardens, but yards vary. Use My Garden frost settings or the zone 4 fall calendar and count backward. See What to plant now, September zone 3, and September zone 5.

Sow These Now

• Radishes and arugula: early September if a few weeks remain before frost. Catalog fall windows run about August 20 to October 1. Fall radishes, fall arugula.
• Spinach and lettuce: last typical chance early in the month. Keep seedbeds cool and moist. Fall spinach, fall lettuce.
• Kale: late from seed. Transplants only if already started. Fall kale.
• Broccoli and cabbage: too late to seed for a fall head. A 70-day cabbage sown now will not head before typical frost. Use transplants already in, or grow fast greens instead. Fall broccoli, fall cabbage.

Cover Crops on Spent Beds

After early-month sowings, switch spent beds to winter rye. It can go in until about 2 weeks after first frost, near October 9 at zone defaults. Oats need 6 weeks before first frost, so they are past. When to sow cover crops by zone.

Wait on Garlic

Do not plant garlic in September in zone 4. Plant later when soil has cooled. Order seed garlic now if you have not. Garlic by zone.

Next Steps

Sow a short row of radishes or greens in the first half of the month if frost settings allow. Clear one spent bed for winter rye. Put seed garlic on the October list.